BackgroundAdolescent girls aged 15–19 bear a disproportionate burden of negative sexual and reproductive health outcomes in low- and middle-income countries. Research from several high-income countries suggests that early age at menarche is an important determinant of sexual and reproductive health. We conducted this systematic review to better understand whether and how early menarche is associated with various negative sexual and reproductive health outcomes in low- and middle-income countries and the implications of such associations.MethodsWe systematically searched eight health and social sciences databases for peer-reviewed literature on menarche and sexual and reproductive health in low- and middle-income countries. Two reviewers independently assessed all studies for inclusion, overall quality and risk of bias, and performed data extraction on all included studies.ResultsTwenty-four articles met all inclusion criteria–nine of moderate quality and fifteen with several methodological weaknesses. Our review of the minimal existing literature showed that early menarche is associated with early sexual initiation, early pregnancy and some sexually transmitted infections in low- and middle-income countries, similar to what has been observed in high-income countries. Early menarche is also associated with early marriage–an association that may have particularly important implications for countries with high child marriage rates.ConclusionsEarly age at menarche may be an important factor affecting the sexual and reproductive health of adolescent girls and young women in low- and middle-income countries. More research is needed to confirm the existence of the identified associations across different settings and to better understand the process through which early menarche and other markers of early pubertal development may contribute to the increased vulnerability of girls to negative sexual and reproductive health outcomes in low- and middle-income countries. Given the association of early menarche with early marriage, ongoing efforts to reduce child marriage may benefit from targeting efforts to early maturing girls.

Background: Strategies are urgently needed to mitigate the risk of zoonotic disease emergence in southern China, where pathogens with zoonotic potential are known to circulate in wild animal populations. However, the risk factors leading to emergence are poorly understood, which presents a challenge in developing appropriate mitigation strategies for local communities.Methods: Residents in rural communities of Yunnan, Guangxi and Guangdong provinces were recruited and enrolled in this study. Data were collected through ethnographic interviews and field observations, and thematically coded and analysed to identify both risk and protective factors for zoonotic disease emergence at the individual, community and policy levels.Results: Eighty-eight ethnographic interviews and 55 field observations were conducted at nine selected sites. Frequent human-animal interactions and low levels of environmental biosecurity in local communities were identified as risks for zoonotic disease emergence. Policies and programmes existing in the communities provide opportunities for zoonotic risk mitigation. Conclusions:This study explored the relationship among zoonotic risk and human behaviour, environment and policies in rural communities in southern China. It identifies key behavioural risk factors that can be targeted for development of tailored risk-mitigation strategies to reduce the threat of novel zoonoses.